Generally, when the peak luminance of original image data is higher than the peak luminance of a display device, the original image data may be converted in accordance with the peak luminance of the display device so that the original image data can be displayed on various display devices having different levels of peak luminance. An operation of converting the peak luminance of original image data in accordance with the peak luminance of a display device is called tone mapping.
A High-Dynamic-Range (HDR) technique is a scheme for generating optimal image data by generating a plurality of image data having different levels of luminance in one scene and by composing the plurality of image data. For example, in one scene including subjects having a wide range of luminance, such as a scene in which the sun in the bright sky coexists with a dark hill in the shadows, images with moderate luminance in each of the respective subjects are selected and composed using the HDR technique, thereby expressing both the bright sky and the dark hill with appropriate luminance in a single image.